A numerical study has been carried out on the formation of a water aerosol in a laminar stagnation point flow. The two impinging streams were at different temperatures and initial supersaturations. As the streams of vapor mixed, homogeneous nucleation occurred along with condensational particle growth. Attention has been focused on the impact of the mixing rate of the two streams on the aerosol dynamics. The mixing rate is determined by the velocity gradient of the flow. High mixing rates were found to reduce the aerosol mass at the stagnation point of the flow. However, particle number densities were not affected by the velocity gradient of the flow as the aerosol dynamics adjusted themselves to the different conditions.